Dry mouth, otherwise known as Xerostomia, means that you have less saliva. This means that there will be less oxygen in your mouth. When oxygen is lacking an anaerobic environment will be created which is perfect for the production of bacteria. Bacteria in the mouth will create sulphur gases which will give you bad breath and also leave a bad taste in your mouth.
More on how to cure your bad breath here
Bad Breath
Cure bad breath
